U.S. patent application number 13/763334 was filed with the patent office on 2013-08-15 for method and apparatus for controlling and powering an electronic accessory from a mobile digital device.
The applicant listed for this patent is Nagesh Challa, Venkata T. Gobburu. Invention is credited to Nagesh Challa, Venkata T. Gobburu.
Application Number | 20130207481 13/763334 |
Document ID | / |
Family ID | 48945020 |
Filed Date | 2013-08-15 |
United States Patent
Application |
20130207481 |
Kind Code |
A1 |
Gobburu; Venkata T. ; et
al. |
August 15, 2013 |
Method and Apparatus for Controlling and Powering an Electronic
Accessory from a Mobile Digital Device
Abstract
Various energy harvesting and control techniques are used to
power and control electronic accessories from the audio output
channels and microphone input channel of mobile digital devices
while preserving audio input and output functionality. One
technique uses one of the stereophonic audio channels to generate
power, and the other in conjunction with the microphone jack to
enable bi-directional communications while preserving audio input
and output. Another technique allows a low powered electronic
accessory with bi-directional communications to be supported while
simultaneously supporting audio input & stereo output. These
techniques facilitate the ability to play music, narration and
instruction and to receive oral responses and instruction with no
perceived loss or gaps, even while using the audio jack of a mobile
digital device to harvest energy and bi-directional
communication.
Inventors: |
Gobburu; Venkata T.; (San
Jose, CA) ; Challa; Nagesh; (Saratoga, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gobburu; Venkata T.
Challa; Nagesh |
San Jose
Saratoga |
CA
CA |
US
US |
|
|
Family ID: |
48945020 |
Appl. No.: |
13/763334 |
Filed: |
February 8, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61597307 |
Feb 10, 2012 |
|
|
|
Current U.S.
Class: |
307/104 |
Current CPC
Class: |
H04B 5/0031 20130101;
H04B 5/0037 20130101; H04R 3/00 20130101; H04R 5/04 20130101; H04B
5/0006 20130101; H04R 2420/03 20130101; H04B 5/06 20130101; H04R
3/12 20130101 |
Class at
Publication: |
307/104 |
International
Class: |
H04B 5/00 20060101
H04B005/00 |
Claims
1. An apparatus for powering and controlling an electronic
accessory from a mobile digital device, comprising: a right audio
channel input terminal; a left audio channel input terminal; a
microphone output terminal; a signal selector coupled to the right
audio channel input terminal and to the left audio channel input
terminal, and having a power output for providing a power carrier
from one or both of the right and left audio channel input
terminals, a transmit data output for providing transmit data from
one or both of the right and left audio channel input terminals,
and an audio output for providing an audio signal from one or both
of the right and left audio channel input terminals; a signal
integrator coupled to the microphone output terminal for outputting
on the microphone output terminal an integrated signal comprising
an audio signal from an audio input and receive data from a receive
data input; an application logic controller for controlling
interactions between the mobile digital device and the electronic
accessory, the application logic controller having an input coupled
to the transmit data output of the signal selector, and an output
coupled to the receive data input of the signal integrator; and an
energy harvester coupled to the power output of the signal selector
for generating power for the signal selector, the signal
integrator, the application logic controller, and the electronic
accessory from the power carrier.
2. The apparatus of claim 1 further comprising an electronic
accessory, the right audio channel input terminal, the left audio
channel input terminal, the microphone output terminal, the signal
selector, the signal integrator, the application logic controller,
and the energy harvester being included within the electronic
accessory.
3. The apparatus of claim 1 further comprising a power and
communications adapter separate from the electronic accessory, the
right audio channel input terminal, the left audio channel input
terminal, the microphone output terminal, the signal selector, the
signal integrator, the application logic controller, and the energy
harvester being included within the power and communications
adapter.
4. The apparatus of claim 1 wherein the signal selector comprises:
a conductor coupling the power output to a first one of the right
and left audio channel input terminals; carrier detect logic
coupled to the first one of the right and left audio channel input
terminals; a first switch coupled to the carrier detect logic, the
first switch having an input coupled to a second one of the right
and left audio channel input terminals different from the first one
of the right and left audio channel input terminals, and further
having a first output comprising the audio output, and a second
output; and an analog-to-digital converter having an input coupled
to the second output of the switch and an output comprising the
transmit data output.
5. The apparatus of claim 4 wherein the application logic
controller comprises a transmission request generator; and wherein
the signal integrator comprises: a digital-to-analog converter
having an input comprising the receive data input, and an output;
and a second switch having a first input coupled to the output of
the digital-to-analog converter, a second input comprising the the
audio input, an output coupled to the microphone output terminal,
and a control terminal coupled to the transmission request
generator.
6. The apparatus of claim 1 wherein the audio output comprises a
first channel and a second channel; and wherein the signal selector
comprises: a first high pass filter having an input coupled to a
first one of the right and left audio channel input terminals, and
an output comprising the power output; a second high pass filter
having an input coupled to a second one of the right and left audio
channel input terminals different from the first one of the right
and left audio channel input terminals, and an output; a
demodulator having an input coupled to the output of the second
high pass filter, and an output comprising the transmit data
output; a first low pass filter having an input coupled to the
first one of the right and left audio channel input terminals, and
an output comprising the first channel of the audio output; and a
second low pass filter having an input coupled to the second one of
the right and left audio channel input terminals, and an output
comprising the second channel of the audio output.
7. The apparatus of claim 6 wherein the application logic
controller comprises a transmission request generator; and wherein
the signal integrator comprises: a digital-to-analog converter
having an input comprising the receive data input, and an output;
and a switch having a first input coupled to the output of the
digital-to-analog converter, a second input comprising the the
audio input, an output coupled to the microphone output terminal,
and a control terminal coupled to the transmission request
generator.
8. The apparatus of claim 1 wherein the audio output comprises a
first channel and a second channel; wherein the power output
comprises a first power output component and a second power output
component; wherein the transmit data output comprises a first
transmit data output component and a second transmit data output
component; and wherein the signal selector comprises: a first high
pass filter having an input coupled to a first one of the right and
left audio channel input terminals, and an output comprising the
first power output component; a first demodulator having an input
coupled to the output of the first high pass filter, and an output
comprising the first transmit data output component; a second high
pass filter having an input coupled to a second one of the right
and left audio channel input terminals different from the first one
of the right and left audio channel input terminals, and an output
comprising the second power output component; a second demodulator
having an input coupled to the output of the second high pass
filter, and an output comprising the second transmit data output
component; a first low pass filter having an input coupled to the
first one of the right and left audio channel input terminals, and
an output comprising the first channel of the audio output; and a
second low pass filter having an input coupled to the second one of
the right and left audio channel input terminals, and an output
comprising the second channel of the audio output.
9. The apparatus of claim 8 wherein the application logic
controller comprises a transmission request generator; and wherein
the signal integrator comprises: a digital-to-analog converter
having an input comprising the receive data input, and an output;
and a switch having a first input coupled to the output of the
digital-to-analog converter, a second input comprising the the
audio input, an output coupled to the microphone output terminal,
and a control terminal coupled to the transmission request
generator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 61/597,307 filed Feb. 10, 2012, which
hereby is incorporated herein in its entirety by reference
thereto.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to mobile digital devices and
electronic accessories therefor, and more particularly to
controlling and powering electronic accessories from mobile digital
devices.
[0004] 2. Description of the Related Art
[0005] Mobile phones have become ubiquitous. Part of the
explanation for the explosive growth is the fact that there has
been a tremendous upsurge in the availability of applications.
Gaming and social networking applications abound side by side of
serious applications to enhance productivity, view documents and so
on. An equally interesting trend is the surge in mobile phone
accessories. For a long time accessories were mostly in extending
the audio capabilities. Headphones of various kinds and noise
cancelling headphones became mainstream products. Health monitoring
devices such as blood pressure cuffs and credit card readers are
other examples. Bluetooth brought about a proliferation of tiny,
wireless audio accessories. Email focused keyboard accessories
found their way to the market to overcome the tightly spaced,
cramped keypads on the mobile phone. As mobile phones became more
computationally more powerful and sported high quality displays,
the accessories have also evolved. A number of accessories and
applications have been developed for the iOS platform that covers
the iPhone, iTouch and iPad device types.
[0006] Health and fitness has become a ripe area as evidenced by
the following examples.
[0007] The Nike+iPod Sports Kit is a device which measures and
records the distance and pace of a walk or run; Nike+ iPod,
Wikipedia article http://en.wikipedia.org/wiki/Nike%2BiPod. It has
a small transmitter device attached to or embedded in a shoe, which
communicates with either the Nike+ Sportband, a receiver plugged
into an iPod Nano, or directly with a 2nd, 3rd, or 4th Generation
iPod Touch, iPhone 3GS or iPhone 4 or a Nike+Sportwatch. If using
the iPod or the iPhone 3GS, iTunes software can be used to view the
walk or run history. The kit includes two pieces: a piezoelectric
sensor with a Nordic Semiconductor nRF2402 transmitter that is
mounted under the inner sole of the shoe and a receiver that
connects to the iPod. They communicate using a 2.4 GHz wireless
radio. As the sensor battery cannot be replaced, a new one must be
purchased every time the battery runs out.
[0008] You can check your blood pressure using an iOS device such
as the iPhone, iTouch or iPad. Two market available devices are the
iHealth BP3 (iHealth BP3 Blood Pressure Monitor,
http://www.ihealth99.com/ihealth/bp3.html) and the Withings Blood
Pressure Monitor (Withings Blood Pressure Monitor,
http://www.withings.com/en/bloodpressuremonitor). Operation is
extremely easy and requires download of an app onto the iOS device,
put on a blood pressure cuff, tap the touchscreen to start the
measurement, and within seconds you have a blood pressure reading
that you can track every day.
[0009] Other examples in the health and fitness area are the FitBit
(Fitbit, http://www.fitbit.com/product) and the Jawbone Up (Jawbone
Up, http://jawbone.com/up).
[0010] Examples in the entertainment section include remote
controllers for stereo equipment.
[0011] Musical instruments are another category. The Piano
Apprentice product is a piano teaching tool for iPad, iPod and
iPhone; see Piano Apprentice,
http://www.ionaudio.com/products/details/piano-apprentice. It is a
lightweight, portable 25-note keyboard with built-in stereo
speakers that deliver piano sound in response to touch. It is a
simple connection to the iPad, iPod or iPhone, download the free
app, and start playing piano.
[0012] Another example of an accessory is the work of Jiang Li, a
NASA scientist who created a 30-pin accessory that allows an iPhone
or iPod touch to be used as a chemical sensor; see "NASA Ames
Scientist Develops Cell Phone Chemical Sensor", 10.30.09,
http://www.nasa.gov/centers/ames/news/features/2009/cell_phone_sensors.ht-
ml. The postage stamp-sized device packs 16 nanosensors that allow
for detection and identification of low concentrations airborne
ammonia, chlorine gas, and methane. Connected to an iPhone or iPod
touch's Dock port and used with a special app, the system can send
detection data to another device over a cellular or Wi-Fi
network.
[0013] Many of the available mobile phone accessories are battery
operated. Communication between the mobile phone and the accessory
takes place over standard interfaces such as the wireless Bluetooth
or over wired connections such as USB. It is not an ideal because
it requires periodic replacement of the battery and in some cases
user aggravation because of untimely replacements.
[0014] The IPHONE.RTM. mobile digital device available from Apple
Computer Inc. of Cupertino, Calif., USA, allows limited access to
the mobile phone's internal battery and communications through a
proprietary connector. Accessories designed specifically with this
family of mobile digital devices are designed to work with this
proprietary connector. This controlled proprietary interface allows
a limited amount of power to be drawn from the mobile digital
device and also obtains bi-directional communication capabilities.
The two drawbacks of this approach are that accessories have to be
purpose built for these proprietary interfaces and often require a
royalty payment.
[0015] Power and communications for accessories has been achieved
using the headset audio port of the mobile phone. An interface of
this type using a 3.5mm, 4 connector audio port is disclosed in
Ye-Sheng Kuo et al., "Hijacking Power and Bandwidth from the Mobile
Phone's Audio Interface," ACM DEV'10: Proceedings of the First ACM
Symposium on Computing for Development, December 2010. Kuo et al.
use the right audio channel to provide a signal for power
harvesting purposes, and the left audio channel and the microphone
channel for bi-directional communications.
BRIEF SUMMARY OF THE INVENTION
[0016] While the approach taken by Kuo et al. may allow a mobile
phone to interface with a range of external peripherals, it
precludes the use of the headset audio port for audio input and
output. This preclusion is disadvantageous for the use of
electronic accessories in applications wherein audio input and/or
output are needed.
[0017] One embodiment of the present invention is an apparatus for
powering and controlling an electronic accessory from a mobile
digital device, comprising a right audio channel input terminal; a
left audio channel input terminal; a microphone output terminal; a
signal selector coupled to the right audio channel input terminal
and to the left audio channel input terminal, and having a power
output for providing a power carrier from one or both of the right
and left audio channel input terminals, a transmit data output for
providing transmit data from one or both of the right and left
audio channel input terminals, and an audio output for providing an
audio signal from one or both of the right and left audio channel
input terminals; a signal integrator coupled to the microphone
output terminal for outputting on the microphone output terminal an
integrated signal comprising an audio signal from an audio input
and receive data from a receive data input; an application logic
controller for controlling interactions between the mobile digital
device and the electronic accessory, the application logic
controller having an input coupled to the transmit data output of
the signal selector, and an output coupled to the receive data
input of the signal integrator; and an energy harvester coupled to
the power output of the signal selector for generating power for
the signal selector, the signal integrator, the application logic
controller, and the electronic accessory from the power
carrier.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0018] FIG. 1 is a schematic block diagram of an electronic
accessory being operated from a mobile digital device.
[0019] FIG. 2 is a schematic block diagram of an electronic
accessory being operated from a mobile digital device through a
power and communications adapter.
[0020] FIG. 3 is a schematic block diagram of a general
implementation for powering and communicating with an electronic
accessory from an audio connector of a mobile digital device.
[0021] FIG. 4 is a block schematic diagram of an implementation for
providing power and communications for an electronic accessory from
an audio connector of a mobile digital device, in which audio
output is needed on only one of the audio output channels.
[0022] FIG. 5 is a multi-part graph shows illustrative signals for
the implementation shown in FIG. 4.
[0023] FIG. 6 is a block schematic diagram of an implementation for
providing power and communications for an electronic accessory from
an audio connector of a mobile digital device, in which audio
output is needed in both of the audio output channels.
[0024] FIG. 7 is a block schematic diagram of another
implementation for providing power and communications for an
electronic accessory from an audio connector of a mobile digital
device, in which audio output is needed in both of the audio output
channels.
[0025] FIG. 8 is a block schematic diagram of an implementation for
powering and controlling an electronic accessory for a mobile
digital device without having the application for the electronic
accessory installed on the mobile digital device.
DETAILED DESCRIPTION OF THE INVENTION, INCLUDING THE BEST MODE
[0026] Novel energy harvesting and control techniques are described
herein to power and control electronic accessories for mobile
digital devices while preserving audio input and output
functions.
[0027] One of the techniques uses one of the stereophonic audio
channels to generate power, and the other in conjunction with the
microphone jack to enable bi-directional communications while
preserving audio input and output. This technique is particularly
suitable where true stereophonic sound through the audio jack is
not required. Another one of the techniques allows a low powered
electronic accessory with bi-directional communications to be
supported while simultaneously supporting audio input & stereo
output. These techniques facilitate the ability to play music,
narration and instruction and to receive oral responses and
instruction with no perceived loss or gaps, even while using the
audio jack of a mobile device to harvest energy and bi-directional
communication.
[0028] The term "mobile digital devices" refers to electronic
devices that can be easily carried on the person, and include
mobile communication devices such as mobile phones, smartphones,
multimedia convergence devices such as the IPHONE.RTM. mobile
digital device available from Apple Inc. of Cupertino, Calif., USA,
various mobile digital devices that run the Android operating
system or the Windows mobile operating system, tablet computers
with mobile browsers, and communications enabled personal digital
assistants ("FDA"), mobile entertainment devices such as gaming
devices and audio and video players and other devices suitable for
being carried on the person such as fobs and USB flash drives.
These devices typically have processors or microcontrollers and
internal and/or removable memory and operate in accordance with
computer program components stored in memory. Mobile digital
devices are suitable for many uses, including communications,
entertainment, security, commerce, guidance, data storage and
transfer, and so forth, and may be dedicated for a particular use
or may be suitable for a combination of uses. The techniques
described herein enable the large and growing population of mobile
digital devices, and in particular mobile entertainment devices and
powerful convergence devices, to enable electronic accessories to
be operated and communicated with over the ubiquitous audio jack,
without sacrificing the ability to simultaneously listen to audio
content such as music and record audio content.
[0029] A typical audio connector used on the mobile digital devices
uses four terminals. Two of the terminals, typically denoted as
Left Audio Out and Right Audio Out, typically are used to deliver
audio content from the mobile digital device to audio headphones or
speakers. A third terminal, typically designated as MIC, typically
is used to convey audio signals from an external microphone to the
mobile digital device. The fourth terminal, typically referred to
as Ground, enables the mobile digital device to establish a common
reference level with the external circuitry.
[0030] The ability to operate electronic accessories through the
audio connector involves two basic requirements, the first to
extract or harvest sufficient energy for the electronic accessory,
and the second to establish bi-directional communications between
the mobile digital device and the electronic accessory.
[0031] FIG. 1 is a schematic block diagram of an electronic
accessory 12 being operated from a mobile digital device 10. The
electronic accessory 12 not only is powered by and is in
bi-directional communication with the mobile digital device 10, but
also supports the use of speakers, headphones and microphones 14.
The speakers and microphone 14 may be external to or built into the
electronic accessory 12. The electronic accessory 12 may be
provided with any type of audio connector for external speakers,
headphones and microphones 14.
[0032] FIG. 2 is a schematic block diagram of an electronic
accessory 22 being operated from a mobile digital device 10 through
a power and communications adapter 20. The electronic accessory 22
is powered by and is in bi-directional communication with the
mobile digital device 10. The power and communications adapter 22
also supports the use of speakers, headphones and microphones 24.
The speakers and microphone 24 may be external to or built into the
power and communications adapter 20. The power and communications
adapter 20 may be provided with any type of audio connector for
external speakers, headphones and microphones 24.
[0033] FIG. 3 is a schematic block diagram of a general
implementation for powering and communicating with an electronic
accessory from an audio connector 31 of a mobile digital device 30,
while preserving at least some audio output and audio input
functionality for the mobile digital device 30. An application
resident in memory 37 executes on CPU 36 of the mobile digital
device 30 to transmit and receive suitable signals on the audio
connector 31 for providing power to and communications with the
electronic accessory while preserving the capability for audio
input and output. The right and left audio output channels 32 and
33 may be used singly or in combination to power the electronic
accessory, to communicate with the electronic accessory, and to
deliver audio output. The microphone input may be used to receive
communications from the electronic accessory and to receive audio
input. Depending on the type of device, the mobile digital device
30 may also include a display 35 and/or a keypad 38.
[0034] Each of the left and right audio channels 32 and 33 may
carry an audio signal, a power carrier, a transmit data signal, or
any combination of the foregoing. As used herein, the term "power
carrier" refers to a signal that is designed to transfer power to
an electronic accessory. As used herein, the term "transmit data"
refers to data to the electronic device or a signal containing such
data. The power carrier may additionally serve as a transmit data
signal if modulated in accordance with the transmit data.
[0035] A signal selector 2 selects an audio signal or signals from
one or both of the right and left audio input channel terminals and
provides it as a monaural or stereo audio output.
[0036] The signal selector 2 also selects transmit data ("TD") from
one or both of the right and left audio input channel terminals and
provides the transmit data to application logic controller 8. The
application logic controller 8 in turn provides data output to an
electronic accessory in the appropriate form. The application logic
controller 8 may include a microcontroller with supporting memory
and circuit logic to perform its intended task.
[0037] The signal selector 2 also selects the power carrier ("PC")
and provides it to an energy harvester 6 for generating power for
the signal selector 2, a signal integrator 4, the application logic
controller 8, and the electronic accessory.
[0038] As used herein, the term "receive data" refers to data from
the electronic accessory or a signal containing such data. The
receive data is received from the electronic accessory by the
application logic controller 8, which in turn provides it to the
signal integrator 4. The signal integrator 4 also receives audio
input, and integrates the two signals so that they may be provided
to the mobile digital device 30 over the microphone channel 34.
[0039] The signal selector 2 and the signal integrator 4 may be
implemented in different ways to meet different requirements of
different types of electronic accessories.
[0040] Some types of electronic accessories require continuous
power during an operating cycle of several seconds, several
minutes, or even longer, but may need to communicate only
intermittently during the operating cycle. Other types of
electronic accessories require to be powered only for a few seconds
or less for each operating cycle, but need to communicate while
powered up. In some instances monaural audio is sufficient when the
electronic accessory is in use, while in other instances
stereophonic audio is desired or required.
[0041] FIG. 4 is a block schematic diagram of an implementation 40
for providing power and communications for an electronic accessory
from an audio connector of a mobile digital device, in which audio
output is needed on only one of the audio output channels. The
implementation 40 is useful in situations wherein the electronic
accessory needs to be powered up continuously during operating
cycles of several seconds, several tens of seconds, or even longer,
even though it may need to communicate only intermittently during
the operating cycles. However, the implementation 40 may also be
used for operating cycles of a few seconds or less during which
communication may be needed. In the illustrative implementation 40,
the right audio channel carries the power carrier from the mobile
digital device for use by energy harvest circuit 41 to provide
power to the implementation 40 as well as to the electronic
accessory, while the left audio output channel carries the audio
output and the transmit data from the mobile digital device. The
application stored in the memory 37 and executed on the CPU 36 of
the mobile digital device 30 (FIG. 3) has full a priori knowledge
about the timing, data communications, and power requirements of
the electronic accessory, so that when needed it can indicate to
the accessory either imminent or ongoing transmission of data. The
power carrier on the right audio channel may be synchronized to
indicate whether there is need to transmit any digital information
to the electronic accessory. Illustratively, the absence of the
power carrier may indicate need to transmit digital information to
the electronic accessory. The implementation 40 therefore has a
carrier detect logic ("CDL") circuit 42 that functions as a
detector for the power carrier. The carrier detect logic circuit 42
may be implemented in any desired way, either as logic gates or in
code running on the microcontroller or processor in the application
logic controller 50.
[0042] The output of the power carrier detect logic 42 is a binary
control signal that indicates either the presence or absence of the
power carrier, and is used to control a switch 43. Switch 43 routes
the signal on the left audio output channel to application logic
controller 50 through an analog-to-digital converter 45 for sending
digital information to the electronic accessory when the binary
control signal is active (illustratively indicated by an absence of
the power carrier), and to a speaker or audio connector 47 for
supplying monaural audio to the user when the binary control signal
from the carrier detect logic 42 is inactive (illustratively
indicated by the presence of the power carrier). The energy harvest
circuit 41 is provided with sufficient power storage to power the
electronic accessory for short periods of time while the power
carrier signal is absent. Although the time period varies depending
on the application, a period of three seconds is an example of a
suitable time period. Restricting the transmission of data from the
mobile digital device to small periods of time in comparison to the
storage capacity of the energy harvest circuit 41 enables
information exchange from the mobile digital device to the
electronic accessory to be done without gaps. Moreover, the
duration of the transmission period may be established to avoid the
presence of perceivable gaps in the normal audio content to the
listener.
[0043] Optionally the monaural audio may be delivered to two
speakers. Furthermore the monaural audio may be further enhanced by
a signal conditioning circuit to modify the listener experience;
for example, simulated stereo wherein frequencies of the audio
signal are selectively delivered to the two speakers, and enhanced
voice signals to accommodate hearing impaired people.
[0044] The application logic controller 50 has full knowledge of
any required digital data transmission to the mobile digital
device. A transmission request generator 52 under control of the
application logic controller 50 generates a binary control signal
referred to as ALC Transmit Request, which is provided to switch
44. When active, the ALC Transmit Request causes the switch 44 to
route the receive data signal from the application logic controller
50 through a digital-to-analog converter 46 to the audio input
channel MIC. When inactive, the ALC Transmit Request causes the
switch 44 to route the output of the microphone to the audio input
channel MIC. This allows the ALC receive data to be available to
the mobile digital device when required.
[0045] FIG. 5 is a multi-part graph which shows illustrative
signals for the left audio output channel, the audio input channel,
the various binary controls, and the normal audio control. When
normal audio is present on the left audio output channel, the power
carrier is present so that the Carrier Detect Logic signal is low
and normal monaural audio is provided to the speaker or audio
output connector. When transmit data is present on the left audio
output channel, the power carrier is absent so that the Carrier
Detect Logic signal goes high and the transmit data is applied to
the input of the Application Logic Controller 50. When a Transmit
Request is generated, the microphone input is interrupted and
receive data is provided to the application.
[0046] While the embodiment of FIG. 4 and FIG. 5 use an
interruption in the power carrier on the right audio output channel
to indicate the presence of transmit data on the left audio output
channel and to cause the carrier detect logic signal to go active
(high), the embodiment of FIG. 4 may be varied by designing the
carrier detect logic 42 to output an active (high) signal when the
power carrier is present and to output an inactive (low) signal
when the power carrier is absent. In this variation, the electronic
accessory remains powered over an operating cycle which may include
frequent communications as needed. While the operating cycle may be
as long as desired, it may be of a limited duration to avoid the
presence of perceivable gaps in the normal audio content to the
listener.
[0047] FIG. 6 is a block schematic diagram of an implementation 60
for providing power and communications for an electronic accessory
from an audio connector of a mobile digital device, in which audio
output is needed or desired in both of the audio output channels.
The implementation 60 is particularly useful for situations wherein
the electronic accessory only needs to be powered up for short
operating cycles during which communication may be needed. The
illustrative implementation 60 includes an energy harvest circuit
66 and an application logic controller 70. One of the audio output
channels, the right channel as exemplified herein, is provided as
an input to a high pass filter 64 and a low pass filter 63. The
other audio output channel, the left channel as exemplified herein,
is provided as an input to a high pass filter 74 and a low pass
filter 73.
[0048] Illustratively, the application on the mobile digital device
generates on the right audio channel a composite of two signals, a
power carrier signal 62 and the normal audio content signal 61
which is expected to be heard by the user on a speaker or headset.
The power carrier signal may be centered on a frequency that is
sufficiently higher than the normal audio output. In the exemplary
implementation described herein the power carrier signal is
centered at 22.5 KHz.
[0049] High pass filter 64 blocks or severely attenuates all
frequencies below a designed cutoff frequency, referred to as fc1
for clarity. A more complete description of a high pass filter may
be done by specifying various parameters such as the following:
"Ap" amount of ripple allowed in the pass band in decibels, "Ast"
attenuation in the stop band in decibels, "Fpbc" pass band cutoff
frequency, and "Fsbc" stop band cutoff frequency (fc1 mentioned
above). In the exemplary implementation 60, suitable illustrative
values for the various parameters of the high pass filter 64 are as
follows: Ap=0.5 decibels, Ast=60 decibels, Fpbc=21 KHz, and Fsbc=16
KHz. Implemented with these values, the high pass filter 64
provides an output that is mainly the power carrier 62 with very
minute quantities of normal audio content (not shown). The energy
harvest circuit 66 is presented with essentially the power carrier
signal and thereby generate the power Vcc needed to operate the
electronic accessory. Alternatively, the energy harvest circuit 66
may be implemented in such a way as to discriminate against audio
frequencies, in which case the high pass filter 64 may be
omitted.
[0050] Low pass filter 63 blocks or severely attenuates all
frequencies above a designed cutoff frequency, referred to as fc2
for clarity. A more complete description of a low pass filter may
be done by specifying various parameters such as the following:
"Ap" amount of ripple allowed in the pass band in decibels, "Ast"
attenuation in the stop band in decibels, "Fpbc" pass band cutoff
frequency, and "Fsbc" stop band cutoff frequency (fc2 mentioned
above). In the exemplary implementation 60, suitable illustrative
values for the various parameters of the low pass filter 63 are as
follows: Ap=0.5 decibels, Ast=60 decibels, Fpbc=16 KHz, and Fsbc=20
KHz. Implemented with these values, the low pass filter 63 provides
an output that is mainly the normal audio content 61 with very
minute quantities of the power carrier (not shown). The right
channel speaker or audio output connector 65 is thereby presented
with the normal audio content expected by the user for this
channel.
[0051] Illustratively, the application on the mobile digital device
generates on the left audio channel a composite of two signals, a
transmit data signal 72 and the normal audio content signal 71
which is expected to be heard by the user on a speaker or headset.
The transmit data signal may be centered on a frequency that is
sufficiently higher than the normal audio output. In the exemplary
implementation described herein the transmit data signal is
centered at 22.5 KHz.
[0052] High pass filter 74 blocks or severely attenuates all
frequencies below a designed cutoff frequency, referred to as fc3
for clarity. A more complete description of a high pass filter may
be done by specifying various parameters such as the following:
"Ap" amount of ripple allowed in the pass band in decibels, "Ast"
attenuation in the stop band in decibels, "Fpbc" pass band cutoff
frequency, and "Fsbc" stop band cutoff frequency (fc3 mentioned
above). In the exemplary implementation 60, suitable illustrative
values for the various parameters of the high pass filter 74 are as
follows: Ap=0.5 decibels, Ast=60 decibels, Fpbc=20 KHz, and Fsbc=16
KHz. Implemented with these values, the high pass filter 74
provides an output that is mainly the transmit data 72 with very
minute quantities of normal audio content (not shown). The output
of the high pass filter 74 is provided to a demodulator 76 to
extract the transmit data, and digitizes and provides it to the
application logic controller 70 for such processing as desired.
[0053] Low pass filter 73 blocks or severely attenuates all
frequencies above a designed cutoff frequency, referred to as fc4
for clarity. A more complete description of a low pass filter may
be done by specifying various parameters such as the following:
"Ap" amount of ripple allowed in the pass band in decibels, "Ast"
attenuation in the stop band in decibels, "Fpbc" pass band cutoff
frequency, and "Fsbc" stop band cutoff frequency (fc4 mentioned
above). In the exemplary implementation 60, suitable illustrative
values for the various parameters of the low pass filter 73 are as
follows: Ap=0.5 decibels, Ast=60 decibels, Fpbc=16 KHz cutoff, and
Fsbc=20 KHz. Implemented with these values, the low pass filter 73
provides an output that is mainly the normal audio content 71 with
very minute quantities of the transmit data (not shown). The left
channel speaker or audio output connector 75 is thereby presented
with the normal audio content expected by the user for this
channel.
[0054] The application logic controller 70 has full knowledge of
any required digital data transmission to the mobile digital
device. A transmission request generator 78 under control of the
application logic controller 70 generates a binary control signal
referred to as ALC Transmit Request, which is provided to switch
67. When active, the ALC Transmit Request causes the switch 67 to
route the receive data signal from the application logic controller
70 through a digital-to-analog converter 68 to the audio input
channel MIC. When inactive, the ALC Transmit Request causes the
switch 67 to route the output of the microphone 69 to the audio
input channel MIC. This allows the ALC receive data to be available
to the mobile digital device when required.
[0055] Many of the functional blocks of FIG. 6 may be implemented
in hardware, software, firmware, or any combination thereof. The
low pass filter 63, high pass filter 64, low pass filter 73, high
pass filter 74, and demodulator 76, for example, may be implemented
in physical circuits. Alternatively, the low pass filter 63, low
pass filter 73, high pass filter 74, and demodulator 76 in
particular may be implemented in software stored in the memory of
the application logic controller 70 and executed by the application
logic controller 70. If desired, the audio input from the
microphone 69 may be digitized (not shown) and processed digitally
along with the receive date by the application logic controller
70.
[0056] FIG. 7 is a block schematic diagram of an implementation 80
for providing power and communications for an electronic accessory
from an audio connector of a mobile digital device, in which audio
output is needed in both of the audio output channels. Like the
implementation 60, implementation 80 is particularly useful for
situations wherein the electronic accessory only needs to be
powered up for brief operating cycles during which it may need to
communicate. However, implementation 80 is further suitable for
situations wherein the electronic accessory has a higher power
requirement. A novelty of this implementation is that both audio
output channels may contain the power carrier signal, the transmit
data signal, and normal audio content. The illustrative
implementation 80 includes an energy harvest circuit 88 and an
application logic controller 90. One of the audio output channels,
the right channel as exemplified herein, is provided as an input to
a high pass filter 84 and to a low pass filter 83. The other audio
output channel, the left channel as exemplified herein, is provided
as an input to a high pass filter 94 and to a low pass filter
93.
[0057] Illustratively, the application on the mobile digital device
generates on the right audio channel a composite of two signals, a
power carrier signal 82 which is modulated, and normal audio
content signal 81 which is expected to be heard by the user on a
speaker or headset. The power carrier signal 82 may be centered on
a frequency that is sufficiently higher than the normal audio
output. In the exemplary implementation described herein, the power
carrier signal is centered at 22.5 KHz. Illustratively, the
application on the mobile device modulates a pure power carrier in
a manner suitable to allow information to be carried on it to form
the modulated power carrier signal 82. As an example, the
modulation may be a Frequency Shift Keying ("FSK") technique,
provided the frequencies used are sufficiently higher than the
normal audio output.
[0058] High pass filter 84 blocks or severely attenuates all
frequencies below a designed cutoff frequency, referred to as fc5
for clarity. Suitable illustrative values for the various
parameters of the high pass filter 84 may be the same as for the
high pass filter 64. Implemented with these values, the high pass
filter 84 provides to the energy harvest circuit 88 an output that
is mainly the power carrier 82 with very minute quantities of
normal audio content (not shown) along with the modulation,
illustratively FSK modulation, which has very little impact on the
performance of the energy harvest circuit 88 in generating the
power Vcc needed to operate the various components of the
implementation 80 as well as the electronic accessory.
[0059] The output of the high pass filter 84 is also provided to a
demodulator 86 which demodulates the power carrier 82 to extract
the transmit data, and digitizes and provides it to the Application
Logic Controller 90 for further processing. Suitable demodulators
are available for a variety of different modulation techniques.
[0060] Low pass filter 83 blocks or severely attenuates all
frequencies above a designed cutoff frequency, referred to as fc6
for clarity. Suitable illustrative values for the various
parameters of the low pass filter 83 may be the same as for the low
pass filter 63. Implemented with these values, the low pass filter
83 provides an output that is mainly the normal audio content 81
with very minute quantities of the power carrier (not shown). The
right channel speaker or audio output connector 85 is thereby
presented with the normal audio content expected by the user for
this channel.
[0061] Illustratively, the application on the mobile digital device
generates on the left audio channel a composite of two signals, a
power carrier signal 92 which is modulated, and normal audio
content signal 91 which is expected to be heard by the user on a
speaker or headset. The power carrier signal 92 may be centered on
a frequency that is sufficiently higher than the normal audio
output. In the exemplary implementation described herein, the power
carrier signal is centered at 22.5 KHz. Illustratively, the
application on the mobile device modulates a pure power carrier in
a manner suitable to allow information to be carried on it to form
the modulated power carrier signal 92. As an example, the
modulation may be a Frequency Shift Keying ("FSK") technique,
provided the frequencies used are sufficiently higher than the
normal audio output.
[0062] High pass filter 94 blocks or severely attenuates all
frequencies below a designed cutoff frequency, referred to as fc7
for clarity. Suitable illustrative values for the various
parameters of the high pass filter 94 may be the same as for high
pass filter 74. Implemented with these values, the high pass filter
94 provides to the energy harvest circuit 88 an output that is
mainly the power carrier 92 with very minute quantities of normal
audio content (not shown) along with the modulation, illustratively
FSK modulation, which has very little impact on the performance of
the energy harvest circuit 88 in generating the power Vcc needed to
operate the electronic accessory and the application logic circuit
90.
[0063] The output of the high pass filter 94 is also provided to a
demodulator 96 which demodulates the power carrier 92 to extract
the transmit data, and digitizes and provides it to the Application
Logic Controller 90 for further processing. Suitable demodulators
are available for a variety of different modulation techniques.
[0064] Low pass filter 93 blocks or severely attenuates all
frequencies above a designed cutoff frequency, referred to as fc8
for clarity. Suitable illustrative values for the various
parameters of the low pass filter 93 may be the same as for the low
pass filter 73. Implemented with these values, the low pass filter
93 provides an output that is mainly the normal audio content 91
with very minute quantities of the transmit data (not shown). The
left channel speaker or audio output connector 95 is thereby
presented with the normal audio content expected by the user for
this channel.
[0065] The power carrier signals 82 and 92 and the energy harvest
circuit 88 may be designed in any desired manner to improve the
efficiency of energy harvesting. One such design technique is to
provide the power carrier signals 82 and 92 180 degrees
out-of-phase with one another. Another such design technique is to
design the power carrier signals 82 and 92 to generate different
voltages.
[0066] The application logic controller 90 has full knowledge of
any required digital data transmission to the mobile digital
device. A transmission request generator 97 under control of the
application logic controller 90 generates a binary control signal
referred to as ALC Transmit Request, which is provided to switch
100. When active, the ALC Transmit Request causes the switch 100 to
route the receive data signal from the application logic controller
90 to the audio input channel MIC through a digital-to-analog
converter 102. When inactive, the ALC Transmit Request causes the
switch 100 to route the output of the microphone 104 to the audio
input channel MIC. This allows the ALC receive data to be available
to the mobile digital device when required.
[0067] Many of the functional blocks of FIG. 7 may be implemented
in hardware, software, firmware, or any combination thereof. The
low pass filter 83, high pass filter 84, demodulator 86, low pass
filter 93, high pass filter 94, and demodulator 96, for example,
may be implemented in physical circuits. Alternatively, the low
pass filter 83, demodulator 86, low pass filter 93, and demodulator
96 in particular may be implemented in software stored in the
memory of the application logic controller 90 and executed by the
application logic controller 90. If desired, the audio input from
the microphone 104 may be digitized (not shown) and processed
digitally along with the receive date by the application logic
controller 90.
[0068] Some of the techniques described above may be combined in
various ways to achieve other implementations with other
characteristics. One such implementation, for example, may use a
broadband signal on each of the audio channel outputs, which
includes the audio and the FSK-modulated high frequency power
carrier simultaneously. This embodiment would be applicable to yet
another niche, namely were the electronic accessory requires
continuous power at a low level.
[0069] FIG. 8 is a schematic block diagram of an audio-powered and
controlled electronic accessory 118 which is being controlled by
the user of a mobile digital device 114 by interacting with an
application on an application website 112 in the cloud 110 rather
than by interacting with a specific application on the mobile
digital device 114. The application website 112 may be accessed
using any desired website access software such as, for example, a
browser or a widget 116. Advantageously, a widget avoids the need
for the user to launch a browser and navigate to a specific browser
page or site. Since the application running on the application
website 112 may control power to the electronic accessory 118, the
application website 112 may withhold power from or terminate power
to the electronic accessory 118 if the user fails a security check,
does not provide or "pay" pre-arranged credentials, runs out of use
credits, or otherwise violates or fails to satisfy some requirement
for initial or continued use of the electronic accessory 118.
Moreover, the electronic accessory 118 may itself contain security
credentials, so that the application running on the application
website 112 may confirm the security credentials before authorizing
access by the mobile digital device 114 to the application website
112.
[0070] An application may be distributed between the mobile digital
device 114 and the cloud 110 if desired. In an illustrative
client-server arrangement, for example, a client portion of the
application may run on the mobile digital device 114 while a server
portion of the application may run on the application website 112.
Highly sensitive operations such as security and financial may be
handled by the server portion of the application, while other
operations such as interfacing with the user may be handled by the
client portion of the application.
[0071] Various functional blocks included herein are described to a
level sufficient for implementation by one of ordinary skill in the
art. Bi-directional communication, for example, may be achieved
through any number of well understood techniques. For example,
Frequency Shift Keying ("FSK") allows the digital bits of
information, i.e. the "1" and "0" states to be represented through
two distinct frequencies. Another well understood technique is to
use Phase Shift Keying ("PSK") to similarly encode the digital
state of the information bits being sent between the electronic
accessory and the mobile digital device. Similarly, Pulse Width
Modulation ("PWM"), wherein the "1" and "0" states are
differentiated by well separated pulse widths, may be used to
represent the digital state of the information being exchanged.
Other useful and suitable implementation details are disclosed in
Ye-Sheng Kuo et al., "Hijacking Power and Bandwidth from the Mobile
Phone's Audio Interface," ACM DEV'10: Proceedings of the First ACM
Symposium on Computing for Development, December 2010, which hereby
is incorporated herein in its entirety by reference thereto.
[0072] Mobile digital device and electronic accessories may include
a processor and a computer-readable medium in any suitable
combination of hardware, firmware and software. Examples of
processors include microprocessors, controllers and logic circuits,
and a processor may be implemented as a multi-core unit or by
multiple processor units. Examples of computer readable media,
which may be realized in a single type of read-only memory or
readable-writable memory or which may include combinations of
different types of memory, include static random access memory
("SRAM"), dynamic random access memory ("DRAM"), FLASH memory,
solid-state memory, magnetic memory, optical memory, and so forth.
Data and programs containing processor-executable instructions for
operating the mobile personal digital device and implementing
various applications including applications for interfacing with
electronic accessories may be stored in the computer-readable
medium and executed by the processor.
[0073] The various embodiments of the invention described herein
are illustrative. Variations and modifications of the embodiments
disclosed herein are possible, and practical alternatives to and
equivalents of the various elements of the embodiments would be
understood to those of ordinary skill in the art upon study of this
patent document. These and other variations and modifications of
the embodiments disclosed herein may be made without departing from
the scope and spirit of the invention, as set forth in the
following claims.
* * * * *
References